What is color? - Colm Kelleher

Šta je boja? - Kolm Keler (Colm Kelleher)

Prevodilac: Milena Dukić Lektor: Tatjana Jevdjic

One of the most striking properties about life is that it has color.

Jedno od najupečatljivijih svojstava života jeste da ima boju.

To understand the phenomenon of color, it helps to think about light as a wave.

Razmišljanje o svetlosti kao o talasu pomaže razumevanju fenomena boje.

But, before we get to that,

Pre nego što dođemo do toga,

let's talk a little bit about waves in general.

hajde da malo pričamo o talasima uopšte.

Imagine you're sitting on a boat on the ocean watching a cork bob up and down in the water.

Zamisli da sediš u čamcu na okeanu i gledaš plutanje plovka gore-dole.

The first thing you notice about the motion is that it repeats itself.

Prva stvar koju primetiš u vezi sa pokretom, jeste da se ponavlja.

The cork traces the same path over and over again... up and down, up and down.

Plovak prati istu putanju iznova i iznova... gore-dole, gore-dole.

This repetitive or periodic motion is characteristic of waves.

Ovaj ponavljajući ili periodični pokret je karakteristika talasa.

Then you notice something else...

Onda primetiš nešto drugo...

using a stopwatch, you measure the time it takes for the piece of cork

koristeći štopericu, izmeriš vreme koje je potrebno plovku

to go over its highest position down to its lowest and then back up again.

da pređe sa najviše pozicije ka najnižoj i onda da se ponovo vrati gore.

Suppose this takes two seconds.

Recimo da mu treba dve sekunde.

To use the physics jargon, you've measured the period of the waves that cork is bobbing on.

Da koristimo žargon iz fizike, izmerio si period talasa u kojem plovak poskakuje.

That is, how long it takes a wave to go through its full range of motion once.

To jest, koliko je potrebno talasu da prođe kroz svoj raspon pokreta jednom.

The same information can be expressed in a different way by calculating the wave's frequency.

Ista informacija se može prikazati na drugi način, izračunavajući talasnu frekvenciju.

Frequency, as the name suggest, tells you how frequent the waves are.

Frekvencija, kao što ime govori, kazuje koliko su talasi frekventni.

That is, how many of them go by in one second.

To jest, koliko ih je u jednoj sekundi.

If you know how many seconds one full wave takes,

Ako znaš koliko sekundi traje jedan talas,

then it's easy to work out how many waves go by in one second.

onda je lako odrediti koliko je talasa u jednoj sekundi.

In this case, since each wave takes 2 seconds, the frequency is 0.5 waves per second.

U ovom slučaju, pošto svaki talas traje 2 sekunde, frekvencija je 0,5 talasa po sekundi.

So enough about bobbing corks... What about light and color?

Dosta o poskakivanju plovka.... šta je sa svetlošću i bojom?

If light is a wave, then it must have a frequency. Right?

Ako je svetlost talas, onda mora imati frekvenciju. Je l' tako?

Well... yes, it does.

Pa...da, tako je.

And it turns out that we already have a name for the frequency of the light that our eyes detect.

Ispostavlja se da već imamo ime za frekvenciju svetlosti koju naše oči detektuju.

It's called color.

Zove se boja.

That's right. Color is nothing more than a measure of how quickly the light waves are waving.

Tako je. Boja nije ništa drugo do mera koliko brzo svetlosni talasi talasaju.

If our eyes were quick enough, we might be able to observe this periodic motion directly,

Da su naše oči dovoljno brze, mogli bismo posmatrati taj periodični pokret direktno,

like we can with the cork and the ocean.

kao što možemo plovak i okean.

But the frequency of the light we see is so high,

Ali frekevencija svetlosti koju vidimo je toliko visoka,

it waves up and down about 400 million million times a second,

da talasa gore-dole oko 400 milion miliona puta u sekundi,

that we can't possibly see it as a wave. But we can tell, by looking at its color, what its frequency is.

tako da je nemoguće da je vidimo kao talas. Ali možemo reći, gledajući u boju, koja je to frekvencija.

The lowest frequency light that we can see is red and the highest frequency is purple.

Najniža frekvencija svetlosti koju možemo videti je crvena, a najviša frekvencija je ljubičasta.

In between all the other frequencies form a continuous band of color, called the visible spectrum.

Sve frekvencije između stvaraju neprekidan niz boja, nazvan vidljivi spektar.

So, what if you had a yellow pencil sitting on your desk?

Šta ako imaš žutu olovku na stolu?

Well, the sun emits all colors of light, so light of all colors is hitting your pencil.

Sunce emituje sve boje svetlosti, tako da svetlost svih boja udara tvoju olovku.

The pencil looks yellow because it reflects yellow light more than it reflects the other colors.

Olovka izgleda žuto zato što reflektuje žutu svetlost više nego ostale boje.

What happens to the blue, purple and red light?

Šta se dešava sa plavom, ljubičastom i crvenom svetlošću?

They get absorbed and the energy they are carrying is turned into heat.

One se apsorbuju i energija koju nose se pretvara u toplotu.

It is similar with objects of other colors.

Slično je i sa objektima drugih boja.

Blue things reflect blue light, red things reflect red light and so on.

Plave stvari reflektuju plavo svetlo, crvene stvari reflektuju crveno svetlo i tako dalje.

White objects reflect all colors of light,

Beli objekti reflektuju sve boje svetlosti,

while black things do exactly the opposite and absorb at all frequencies.

dok crne stvari čine upravo suprotno i apsorbuju sve frekvencije.

This - by the way - is why it's uncomfortable to wear your favorite Metallica t-shirt on a sunny day.

Ovo je usput, razlog zašto je neudobno nositi tvoju omiljenu majicu Metalike po sunčanom danu.